Interface meter problems encountered in acrylic acid production
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I am a process engineer working in acrylic acid production facilities. Those who are familiar with this field should know that the water removal step in the purification process relies on the azeotropic distillation principle using toluene. During operation, I encountered this problem: while adding toluene (containing water) to the reflux tank, the level of the aqueous phase kept rising, due to the continuous presence of water there; meanwhile, water was removed from the bottom of the tank in order to control this level. But after a certain point, the interface suddenly drops steeply. I would like to ask experienced colleagues: is this caused by uneven stratification during the toluene addition process, or are there other factors at play?
With the instrument itself being fine, is it confirmed that the tank is full? The interface level gauge can only take measurements when the tank is full. Also, check whether there are polymers or dirt in the medium.
We are using a float interface meter; shouldn’t it measure the interface position caused by the density difference between water and toluene? Here it is measuring the water level, right? Shouldn’t it be able to display it as long as there is a stratification interface? The polymer you mentioned is definitely not present during the water separation stage, when it comes out from the top of the tower; no dirt can be seen on site either. I just don’t quite understand this phenomenon of mutation
This post was last edited by Pan Dora on 2016-3-11 21:58. For interface floats, measurement must be taken when the tank is full. The water level can be understood only when the tank is full. When all the interface floats are submerged in oil, that is the zero point of the interface. When all the interface floats are submerged in water, it represents the full scale of the interface. For example, the density of water is 1, the density of toluene is 0.86, and the measurement range is 1 meter. When calibrating the interface float with water, filling it with 0.86 meters of water (with no oil above it, only air) represents the zero point for the interface float; this corresponds to a zero liquid level as shown on the DCS. A fill level of 1 meter represents the full scale; in the absence of toluene at the top, a fill level of 0.93 meters corresponds to a liquid level of 50% as indicated on the DCS. The location of oil-water separation can be truly determined only when both oil and water generate buoyancy on the entire float. Half a meter of oil and half a meter of water represents the 50% mark; 25 centimeters of oil and 75 centimeters of water represent the 75% mark (on a 1-meter scale). Therefore, only when the tank is full is it the true measurement value of the interface float. The buoy is based on the principle of variable buoyancy measurement. Changes in buoyancy lead to changes in the force acting on the buoy’s torsion bar. It is extremely small, especially for interface floats, with a very narrow range of forces applied.